Delors, a long-serving Commission president (1985-1994) who was the architect of the euro and the EU's Eastern enlargement, was invited to speak in the European Parliament to commemorate the 20th anniversary of Germany's reunification.
After speaking to a packed Parliament hemicycle in Brussels, the Frenchman was received with a standing ovation which lasted several minutes. He was standing alongside Lothar de Maizière, the first democratically-elected prime minister of the former German Democratic Republic (GDR), who had the task of putting to an end his country, created during the Cold War.
In his speech, Delors recalled the political wisdom of German politicians at the time of reunification, citing Chancellor Helmut Kohl as primary among these.
Kohl, he said, had the courage to abandon his country's national currency, the Deutsche Mark, which was one of the cornerstones of German power. But the Frenchman said that in doing so Kohl strengthened Germany's European and global stature.
Speaking in French, Delors said: "I am not motivated by nostalgia saying this, I'm just a militant today addressing Germany, which is celebrating its reunification, which all member countries are celebrating. Are the values which we inherited from the fathers of Europe still present, still dominant? The legacy which was transmitted to us is mostly about 'why do we want to be together?' more than treaties and inter-institutional arrangements."
Delors also spoke about Germany's "duties" in bringing forward the European project. The alternative, as he described it, is muddling along from one day to the next, thanks to compromises which may be sometimes necessary, but would not open perspectives for the future.
Chancellor Merkel was criticised recently for foot-dragging on a decision to put in place a financial mechanism to bail out bankrupt Greece. Her procrastination weakened the euro and the saga prompted some voices in Germany to call for the reintroduction of the Deutsche Mark and the reinstatement of national sovereignty.
In addition, traditional Franco-German relations, which have often been hailed as the "engine" of the European Union, has lost its traction under the current leadership of Nicolas Sarkozy in France and Chancellor Merkel in Germany. The relations between the two leaders appear to be difficult in many respects.
Delors, whose daughter Martine Aubry is leader of the Socialist opposition party in his native France, made no mention of his country in his speech.
However, Delors' relations with French President Sarkozy and his predecessor, Jacques Chirac, are known for being strained. These tensions were reflected in their exclusion from the 'wise men' groups who drafted the EU's Constitutional Treaty and the Lisbon Treaty, in spite of his expertise and international prestige. Delors did not hide his frustration about this in a recent interview with EurActiv.
Delors's role in German reunification was also highlighted in a recent EurActiv interview of Carlo Trojan, chief negotiator on the integration of the former German Democratic Republic (GDR) into the Federal Republic of Germany.